Microstrip Disk Research Articles

Radiation Improvement of Microstrip Antenna by Metamaterial Superstrate

In this paper, a new approach to enhance the radiation efficiency of microstrip patch antennas by a quarter-wavelength antireflection superstrate is proposed. It is based on dielectric right-handed metamaterial (MM) build with U-shape cells. The moments method in the spectral domain predicts a maximum radiation efficiency of 78% for disk microstrip antenna combined with quarter-wavelength dielectric antireflection superstrate. Design, optimization and characterization of the metamaterial layer are well described. A numerical analysis of the microstrip patch antenna disk with and without metamaterial antireflection layer is performed with commercial specialised software. The results of the simulation show significant performance improvement of the antenna in the presence of the metamaterial antireflection layer. Radiation efficiency, directivity and gain are respectively increased by 9%, 2dBi and 2.6dB. This approach enabled to improve the total radiated power up to 18%.

Delta-sigma modulation microphone sensors employing a resonant tunneling diode with a suspended microstrip resonator

Purpose This paper aims to propose and demonstrate novel microphone sensors based on the frequency delta-sigma modulation (FDSM) technique, which replaces the conventional delta-sigma modulator in the delta-sigma analog-to digital converters. A key of the FDSM technology is to use a voltage-controlled oscillator (VCO) for converting an input analog signal to a 1-bit pulse-density modulated digital signal. High-performance sensors can be realized if the VCO is replaced by an oscillator whose oscillation frequency depends on an external physical parameter. Design/methodology/approach Microphone sensors are proposed based on FDSM that uses a suspended microstrip disk resonator, where the backside ground plane is replaced by a thin metal diaphragm. A resonant tunneling diode (RTD) oscillator is also used, as the performance of these sensors significantly depends on the oscillation frequency. To demonstrate the basic operation of the proposal, prototype devices were fabricated with an InGaAs/AlAs RTD. Findings A satisfactory noise shaping property, which is a significant nature of delta-sigma modulation, was demonstrated over three decades for the prototype device. A sound-sensing peak was also clearly observed when applying 1 kHz sound from a speaker. Practical implications High-performance ultrasonic microphone sensors can be realized if the sensors are fabricated by using a thin InP substrate with high-frequency oscillator design. Originality/value In this study, the authors proposed and experimentally demonstrated novel microphone sensors, which are promising as future ultrasonic sensors that have high dynamic range with wide bandwidth.

Study of Stacked High Tc Superconducting Circular Disk Microstrip Antenna in Multilayered Substrate Containing Isotropic and/or Uniaxial Anisotropic Materials

In this paper, we present a rigorous full-wave analysis able to estimate exactly the resonant characteristics of stacked high Tc superconducting circular disk microstrip antenna. The superconducting patches are assumed to be embedded in a multilayered substrate containing isotropic and/or uniaxial anisotropic materials (the analysis is valid for an arbitrary number of layers). London’s equations and the two-fluid model of Gorter and Casimir are used in the calculation of the complex surface impedance of the superconducting circular disks. Numerical results are presented for a single layer structure as well as for two stacked circular disks fabricated on a double-layered substrate.

A Circular Disc Microstrip Antenna with Dual Notch Band for GSM/Bluetooth and Extended UWB Applications

A microstrip antenna with a circular disc design and modified ground is proposed in this paper. Circular shapes of different size have been slotted out from the radiating patch for achieving extended ultra wideband (UWB) with GSM/Bluetooth bands with maximum bandwidth of 17.7 GHz (0.88-18.6 GHz). Further, characteristic of dual notch band is achieved, when a combination of T and L-shaped slots are etched into the circular disc and ground plane respectively. Change in length of slots is controlling the notch band characteristics. The proposed antenna has rejection bandwidth of 1.3-2.2 GHz (LTE band), 3.2-3.9 GHz (WiMAX band) and 5.2-6.1 GHz (WLAN band) respectively. It covers the frequency range of 0.88-18.5 GHz with the VSWR of less than 2. Also, an equivalent parallel resonant circuit has been demonstrated for band notched frequencies of the designed antenna. The gain achieved by the proposed antenna is 6.27 dBi. This antenna has been designed, investigated and fabricated for GSM, Bluetooth, UWB, X and Ku band applications. The stable gain including H & E-plane radiation pattern with good directivity and omnidirectional behavior is achieved by the proposed antenna. Measured bandwidths are 0.5 GHz, 0.8 GHz, 1.1 GHz and 11.7 GHz respectively.

An Investigation of Shorting Pin Effects on Circular Disc Microstrip Antennas

In this study, shorting pin addition, one of the common bandwidth enhancement techniques, is performed on traditional circular disc microstrip antennas that have three different dielectric substrate thicknesses and designed in three different resonant frequencies. Numbers of added shorting pins and positions of these pins are changed in every step, systematically and different pin combinations are tried for three antennas that design parameters are present in literature. Later, optimal pin combinations that give the intended resonant frequencies and the largest bandwidths are determined. For these optimal combinations, by keeping the resonant frequencies constant, the bandwidths of the antennas are increased to %1.440, %2.780 and % 6.024, respectively. Compared to measurement results in the literature, for bandwidths, significant improvements are obtained. At the same time, it is observed that the technique of shorting pin addition increases the bandwidths in higher percentages on thicker microstrip antennas. For three antennas, it is seen that all pin combinations give similar resonant frequency variations depended on pin positions.

Design of a Circular Disc Microstrip Antenna Loaded By Annular Ring

The research contained in this thesis is a theoretical study of antenna design and calculation of the radiation fields using electric fields integral equation (EFIE) and magnetic field integral equation (MFIE). These equation have been converted, using the method of moments formulation of electromagnetic radiation in this these based onthe bodies of revolution (BoR),which are generated by revolution a planar curve about an axis called axis of symmetry. To find an unknown electric current density on the surface of the conductor ,and both unknowns electric and magnetic density current on the surface of the dielectric which are responsible for the generation of radiationfields in the space for the components (Eθ ,Eφ) ,the surface currents was represented by a set of basis functions that give the Fourier series because the body has a circular symmetry property and then select a set of weighted functions to find a linear system by using Galerkin method which requires that the weighted functions are equal to the complex conjugate of the current JW = )( * .

L-strip proximity fed gap coupled compact semi-circular disk patch antenna

In this article, the analysis of dualband L-strip fed compact semi-circular disk microstrip patch antenna has been presented using circuit theory concept. The antenna parameters such as return loss, VSWR and radiation pattern are calculated. The effect of geometric dimensions of the proposed antenna such as length of vertical and horizontal portion of L-strip is investigated. It is found that antenna resonate at two distinct modes i.e. 1.3GHz and 6.13GHz for lower and upper resonance frequencies respectively. The bandwidth of the proposed antenna at lower resonance frequency is 6.61% (simulated) and 10.64% (theoretical) whereas at upper resonance frequency, it is 6.02% (simulated) and 9.06 % (theoretical). The theoretical results are compared with IE3D simulation results as well as experimental results and they are in close agreement.

Development of Gas Sensors on Microstrip Disk Resonators

Abstract Here it is reported about the development of microwave disk resonators and their employment as transducers in gas sensing devices. The sensors were developed by designing, modeling and realizing microstrip resonators on several microwave substrates, and by depositing sensing films on the disk. The transduction mechanism can be explained through the change in the permittivity value, in a low thickness of the sensing film, due to the interaction with the gas target. Furthermore, due to the microwave penetration on the sensing material, the response depends on volume effect, not only on surface one. These devices own intrinsic stability due to the fact that the resonance frequency value is related to the physical dimensions.

Pattern and frequency reconfigurable monopole disc antenna using PIN diodes and MEMS switches

ABSTRACTDual reconfigurable microstrip disc antenna is investigated in this article starting from conventional disc. Modifications are added to produce three reconfigurable shapes. First is pattern reconfigurability by rotating the radiation pattern 60°. Second is frequency reconfigurability. Third shape is dual reconfigurability that merges between frequency and radiation pattern changes. © 2014 Wiley Periodicals, Inc. Microwave Opt Technol Lett 56:187–195, 2014

Resonant Frequency of Air Gap Tuned Circular Microstrip Antenna with Anisotropic Substrate and Superstrate Layers

Resonant frequency characteristics of air gap tuned circular microstrip antenna with uniaxially anisotropic substrate and superstrate layers is analysed in Hankel Transform domain using recursive equivalent circuit modelling. The effects of uniaxial anisotropy on the resonant frequency are investigated as the function of anisotropy ratio values of substrate and superstrate materials. According to the results, resonant frequency of anisotropic antenna exhibits incremental or decremental shifts with respect to isotropic one due to adjustment of the layer anisotropies and the thickness of the air gap. Thus, it is important to properly adjust layer anisotropies of the circular disk microstrip antenna for its efficient operation in microwave and communication systems applications.

Application of the FCEL method to a microstrip disk antenna with a parasitic director

AbstractThe method of finite coupled elementary lines (FCEL) is used in the analysis of a microstrip disk antenna with a larger parasitic director. A closed form expression of the effective radius for the used structure is proposed. The obtained numerical results are compared with published measurements and good agreement is noticed. © 2009 Wiley Periodicals, Inc. Microwave Opt Technol Lett 51: 1911–1918, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24506

5 GHz HTS power filters with TM-mode microstrip-disk resonators

For RF wireless applications, high-temperature superconducting (HTS) microwave power filters are desired to satisfy the requirements of higher power handling capability, lower intermodulation distortion (IMD), and dimensions that are more compact. In this report, we propose a 5 GHz HTS band bandpass filter (BPF) that has 2 dual-mode resonators using TM 11-mode microstrip-disk (MD) resonators and waveguide line for electromagnetic (EM) coupling between the MDs. The BPF sample with YBCO films on both sides of an MgO (1 0 0) substrate was fabricated, and their RF characteristics of the S parameters, the power, and 3rd IMD (IMD3) were examined. The filter sample exhibited an IMD3 value less than −70 dBc at 10 W input power, and was estimated the half volume of a conventional 4-pole MD BPF.

A Novel Broadband Compact Circular Disk Microstrip Antenna for Wireless Applications

A novel shape of microstrip antenna which is electromagnetically coupled to a conventional circular disk microstrip antenna (CMSA) mounted on a ground plane and spaced by a layer of foam is studied by simulation and experiment to operate at 5.2GHz for Wireless Local Area Networks (WLANs). The novel shape proposed has a size reduction of 85% as compared to the conventional circular disk patch antenna operating at the same frequency. It is found that the bandwidth of this antenna ranges from 4.8GHz up to 6.15GHz considerably when an optimum foam thickness is provided. The suggested design is optimized using the full wave simulation software package Zeland IE3D based on the method of moments (MoM). The experimental results agree well with the simulated one. Microstrip antennas have the attractive features of low proflle, light weight, easy fabrication pro- cess, and conformability, but these antennas inherently sufier from the narrow bandwidth. Since the world is going wireless, current advancements in communication technology and signiflcant growth in the wireless communication market and consumer demand demonstrate the need for smaller, broadband and reliable antennas. Therefore, bandwidth enhancement and size reduction are becoming the major design considerations for practical applications. Several useful techniques applied to improve the bandwidth and size reduction are presented in (1). In particular, adding a capacitive component to the input impedance of the radiating patch that compensate for the inductive component of the feeder by embedding a cutting slots in it such as E-shape (2,3), V- shape (4), and U-shape (5,6) leads to increasing the percentage bandwidth as long as the resonance frequencies of the patch and the slot are close to each other. Moreover, using more than one layer of resonance patch that is coupled electromagnetically to each other instead of planar structure in order to meet the demand of small size will efiectively enable the bandwidth to increase. These parallel layers are incorporated to introduce another resonance. Since the bandwidth is inversely proportional to the dielectric constant r of the substrate, a layer of foam is employed to decrease the efiective dielectric constant eff and increasing the total thickness of the antenna at the same time.

Computation and optimization of resonant frequency and input impedance of a coax‐fed circular patch microstrip antenna

AbstractMicrostrip antennas are important elements of today's wireless communication networks. In their various applications, it is critical to provide wide band operation around the resonant frequency providing good impedance match between the antenna element and the feed. In this study, new, simple, and accurate computation of resonant frequency and input impedance of double‐layered, coaxial fed circular disk microstrip antenna with air gap is performed. In the analysis, new effective radius and permittivity expressions are used in simple and modified form including modal effects. Then, a new approach is proposed to provide input impedance matching at resonant frequency via the application of microgenetic algorithm for wide band operation. The accuracy of theoretical calculations and impedance matching approach are presented for various structural parameters and operational modes of the antenna. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 2263–2267, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22675

Microwave characteristics of interconnects for 4 GHz-band HTS power devices

For applications of high-Tc superconducting HTS filters with microstrip line structure to microwave power devices in linear operations, it is important not only to achieve handling power sufficient for the devices not to break down, but also to decrease the intermodulation distortion (IMD) as much as possible. One of main causes of the IMD is the pattern of the HTS resonators. Other factors we have considered as a cause of IMD are I/O interconnects and thermal conditions inside a filter package. To clarify these influences, we fabricated and examined the model devices that consisted of a YBCO microstrip disk resonator chip with TM11 resonant mode, the I/O interconnects with metal electrodes, and packages with and without the introduction of He gas. As the results of the third-order IMD (IMD3) examinations of the model devices for 4GHz band, it is confirmed that the IMD can be reduced by improving the I/O interconnects and the gas atmosphere inside the power-filter package.

Power handling improvement by an upper conducting layer for 4 GHz-band HTS microstrip-disk filters with dual-mode

We report that 4GHz-band HTS microstrip disk filter has increased the power handling capability by an upper conducting layer for dual-mode with TM11 mode disk resonator. The 4GHz, 0.1GHz-bandwidth YBCO 4-pole disk filter with an upper YBCO small disk-layer for dual-mode was fabricated. With respect to power handling examination, the input–output power measurement of the fabricated filter was carried out in the range of 50–80K. For comparison, the fabrication and power test of the YBCO 4-pole disk filter with a conventional notch for dual-mode were preformed. The measured results of the handling power showed that the filter with a upper conducting layer can handle a power of 10W, up to which the dual-mode disk filter with a notch made an RF break down.

HTS microstrip disk resonator with an upper dielectric layer for 4GHz

We propose HTS microstrip disk resonator with an upper dielectric layer as a candidate resonator structure of HTS compact power filter for 4GHz band. The electromagnetic simulations on the upper dielectric layer examined the current distributions of the HTS resonators that had TM11 mode resonance of about 4 GHz. By the simulations, it is evaluated that of the maximum current density near the end portion of the disk-shape pattern of the resonator with the thick upper-layered structure decreases by roughly 30-50 percent, as compared with that of the resonator without it. Then, we designed and fabricated the resonator samples with and without the upper dielectrics. The RF power measurement results indicated that the upper dielectric layer leads to an increase in handling power.

RF Power Properties of YBCO-Film/LAO Microstrip Disk Resonators for 4 GHz Band

This paper presents RF power properties of YBCO films on LaAlO 3 substrate examined using microstrip disk shape-patterned resonators for around 4 GHz. Characterization of the YBCO films for the resonators was carried out. For input-output power measurement, the resonators with the condition of strong I/O couplings were designed and fabricated. The RF power properties of the resonators at cryogenic temperatures were measured. The resonator condition to obtain the handling power over 10 W at 30 and 70 K was confirmed. The temperature dependence of the break-down powers at 4GHz for the resonators showed two broad peaks. We discuss the unique phenomenon with magnetic flux model, as referred to the YBCO films characteristics results.

EXTENDED CAVITY MODEL ANALYSIS OF STACKED CIRCULAR DISC

Stacked microstrip antennas deserve special attention due to their advantageous properties like dual frequency operation and wide bandwidth. In the present communication a theoretical model for single stacked microstrip disc antenna is proposed using extended cavity model. The method of analysis by this model is easier and intuitive than the full wave analysis. Single stacked microstrip disc antenna with co-axial feed locations at different radial positions is analyzed with this model taking different ratios of patch sizes. Antenna properties like return loss, input impedance, gain and radiation efficiency are calculated with the proposed model different cases and compared with the simulated and experimental results. The results are in fairly good agreement.

LOADED MICROSTRIP DISK RESONATOR EXHIBITS ULTRA-LOW FREQUENCY RESONANCE

In this paper a novel method of generation of ultra- low resonance in a microstrip disk resonator is presented. The disk resonator is loaded with series L-C circuit across a selective location in the disk via a thin shorting pin. It is shown that in loaded disk resonator, the lowest resonance observed is in VHF range whereas the unloaded disk had a fundamental resonance at 1.76 GHz. This resonance is slightly offset from the series resonant frequency of L- C circuit. and it depends on the disk radius as well. Using IE3D, a commercial MoM solver, the said structure is simulated. The experimental results agree well with the simulated results. A closed form expression for computing the resonant frequency is given.